More than 50 riders are expected to turn out today to inaugurate a series of women-only bicycle rides aimed at improving gender balance in cycling.

Dubbed "Biker Chicks," the group is intended to help more women and girls discover the joys of getting out on two wheels in Sonoma County.

"I'm thrilled to say that I don't know at least half of the people who are coming, which is great," said Sandra Lupien, outreach director for the Sonoma County Bicycle Coalition, a primary organizer of the ride series.

The idea was first floated last year on Facebook by Supervisor Shirlee Zane in response to a Sonoma County Transit Authority report that said women accounted for only 21 percent of local bicycle commuters.

Even as a relatively athletic person who has enjoyed swimming, horseback riding and hiking, Zane said she still found the idea of biking on the same roads as cars "a little intimidating."

But she rediscovered the joy of cycling last summer and hopes the Biker Chick rides will "get people out riding bikes who want to but have been afraid of it."

The bike coalition, the Sonoma County Regional Parks Foundation and HillJillys Women's Bike Club have joined together as co-hosts of the rides, scheduled from 2-5 p.m. today, May 6 and June 10.

The routes will accommodate beginner-level riders, though the rides gradually will increase in length and difficulty, Lupien said.

The first ride will be over-and-back from Santa Rosa to Sebastopol on the Joe Radota Trail, with a stop at Coffee Catz for refreshments.

Participants should bring water bottles, helmets and a snack, and meet at the fish sculpture at Gateway Park on Santa Rosa Avenue, across from Santa Rosa City Hall.

Pre-registration is preferred.

More information is available by emailing events@BikeSonoma.org, online at www.BikeSonoma.org/BikerChicks or by calling 545-0153.

You can reach Staff Writer

Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.